Anyway, just about everyone seems to recommend vitamin C for avoiding/surviving a cold. But while wondering exactly how effective it really is I found this somewhat sad little snippet at webmd.com:
The average adult who suffers with a cold for 12 days a year would still suffer for 11 days a year if that person took a high dose of vitamin C every day during that year.
Which I suppose means that my sporadic little doses probably aren't doing anything at all, except feeding my sweet tooth and delivering, potentially, a little placebo effect.
Mayo Clinic reckons that if you develop a cold while taking vitamin C (ie. this probably does not apply to me or other casual users) you can expect about a 10% reduction in the duration of the cold (15% for children), but there are no significant benefits if you only start taking it after the onset of a cold.
The real winners with vitamin C are people in extreme circumstances. If you're a soldier in the sub-arctic, a skier or a marathon runner, you could use vitamin C to cut your risk of developing a cold by about 50%. Some people get all the perks.
